CVE-2026-39861: Claude Code Sandbox Escape via Symlink

# CVE-2026-39861: Claude Code Sandbox Escape via Symlink

https://gcdradar.vercel.app/incidents/cve-2026-39861-claude-code-sandbox-escape-via-symlink · AIR-2026-0596 · closed 2026-04-21

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability)
- Fix status: Fix status unknown
- First reported: 2026-04-21
- AI role: Attack on AI
- Products: Claude Code
- CVE ids: CVE-2026-39861
- CVSS: 10

## Summary

Claude Code permitted sandboxed processes to create symlinks outside the workspace, causing unsandboxed operations to write to arbitrary locations. This enabled a sandbox escape and potential code execution.

## What to do

No action recorded; read the sources below and the vendor's advisory.

## Latest updates

- 2026-04-21: CVE-2026-39861: Claude Code is an agentic coding tool. (https://nvd.nist.gov/vuln/detail/CVE-2026-39861)
- 2026-04-21: CVE-2026-39861: Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace (https://github.com/advisories/GHSA-vp62-r36r-9xqp)

## Sources

- 2026-04-21 GitHub Advisory Database: CVE-2026-39861: Claude Code: Sandbox Escape via Symlink Following Allows Arbitrary File Write Outside Workspace https://github.com/advisories/GHSA-vp62-r36r-9xqp
- 2026-04-21 NVD: CVE-2026-39861: Claude Code is an agentic coding tool. https://nvd.nist.gov/vuln/detail/CVE-2026-39861

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.